无铅压电陶瓷的缺陷调控与性能提高机理

Recently, lead-free piezoceramics have received much attention worldwide because of increasing environmental concerns. Improving piezoelectric response as much as possible is the most critical issue. It is widely accepted that various defects, which form easily in lead-free ceramics, may result in serious problems, such poor reproducibility and inferior piezoelectric performances. However, the underlying mechanism remains unclear. Taking the most popular (K, Na)NbO3 (KNN)-based ceramics as an example, the current proposal will focus on defect engineering and property enhancement in this system. Firstly, the state of the art techniques, such as high-resolution TEM and synchrotron X-ray absorption fine structure analysis, will be used to characterize the defects existing in KNN ceramics. And then, multi-scale piezoelectric property measurements will be adopted, resulting in direct correlations between defects and piezoelectric performances. Theoretical calculations will also play an important role in understanding the function of defects on microscopic as well as macroscopic properties. Eventually, improved reproducibility and enhanced piezoelectricity is possible to be realized by means of defect engineering. This project will reveal the roles of defects in KNN-based materials, which will shed light on further development of high-performance lead-free piezoceramics.

无铅压电陶瓷因其对环境友好无污染成为近年来的研究热点，而增强其压电性能是当前的首要任务。现有研究表明缺陷对无铅压电陶瓷性能及工艺重复性都有巨大影响；但其作用机理仍不清晰。本项目将选取具有代表性的铌酸钾钠（KNN）基无铅压电陶瓷体系，研究缺陷的表征、调控及其对性能的影响机理。首先利用高分辨透射电镜、同步辐射X射线吸收精细结构分析等多种方法精确表征样品中不同的缺陷类型及含量；进而采取实验测试与理论计算相结合的方法厘清缺陷与宏微观压电特性之间的对应关系，勾画出高性能无铅压电陶瓷中缺陷优化设计的图像；最终有目的地进行缺陷调控从而提高工艺重复性及进一步提升压电性能。本项目成果将明确缺陷对无铅压电陶瓷性能的影响机理和作用规律，有利于推动高性能无铅压电陶瓷的快速发展，并为加速其大规模实际应用奠定坚实的理论和技术基础。

压电材料因可实现电能与机械能的相互转换而被广泛应用于航空、航天、通讯、医疗等众多重要领域。在压电陶瓷材料中，以锆钛酸铅陶瓷为代表的含铅压电陶瓷因其性能优异而应用最为广泛。然而，基于环境保护的迫切要求，以及应对可能随时到来的无铅化变革对我国压电产业造成的巨大影响，掌握高压电性能和较好温度稳定性的无铅压电陶瓷的制备方法并研究其性能提高机理具有重大意义。申请人及团队围绕项目计划书中的三个研究内容，系统开展了关于缺陷控制来调控陶瓷性能的研究。使用高分辨透射电镜、同步辐射X射线衍射、压电铁电测试系统等多种表征手段，并与理论计算相结合，取得了一些列突破性成果：(1) 通过设计材料组分和调控制备工艺，得到了含有不同缺陷种类和缺陷浓度的无铅压电陶瓷，并对缺陷进行了精确表征。(2) 厘清了缺陷对材料宏观电学性能的作用规律，并进一步探明了缺陷对压电性能的影响机制。(3) 开发出了具有高压电响应和出色温度稳定性的无铅压电陶瓷体系。(4) 通过缺陷调控，大幅度提高了无铅压电陶瓷的工艺重复性，为加速其大规模推广应用奠定了理论与技术基础。在Journal of the American Chemical Society, ACS Applied Materials & Interfaces等期刊共发表SCI论文19篇。本项目的成果明确了缺陷对无铅压电陶瓷性能的影响机理和作用规律，实现了缺陷对宏观性能的调控，极大推动了高性能无铅压电陶瓷的快速发展。